Albert Kennedy of Vincennes, Ind. walked into the middle of Highway 41 North at about 1:30 a.m., and was fatally struck, according to a statement from the Knox County Sheriff's Office in Indiana.

Kennedy was pronounced dead at the scene.

Investigators in Indiana are still probing the crash, the statement said.

Aldean took to Twitter to mourn Kennedy's death.

"With a heavy heart, I'm sad to say that a man passed away last night after stepping out in front of my bus in Indiana," Aldean wrote Monday afternoon. "In all the years I've been touring and all the miles we've driven, nothing prepares you for something like this to happen. I'm praying for Albert Kennedy's family and friends today and ask that you do the same."